Back rest supporting structure for chairs



March 8, 1955 D D BACK REST SUPPORTING STRUCTURE FOR CHAIRS Filed July17, 1951 United States Patent BACK REST SUPPORTING STRUCTURE FOR CHAIRSGlenn D. Wood, Elkhart, Ind., assignor to Domore Chair Company, Inc.,Elkhart, Ind., a corporation of Indiana Application July 17, 1951,Serial No. 237,232

Claims. (Cl. 155-156) This invention relates to improvements in backrest supporting structures for chairs and it consists of the mattershereinafter described and more particularly pointed out in the appendedclaims.

The invention is more particularly concerned with structures of thiskind wherein the back rest is disposed upon the upper end of a pair ofconnected laterally spaced uprights, such as shown in the Fields andWood Patent 2,345,926 of April 4, 1944.

One of the objects of the present invention is to provide in a structureof this kind, simple and efficient means for attaching the back rest tothe supporting upright members whereby the back rest is not only capableof a limited forward and rearward rocking movement thereon, but can alsobe raised or lowered relative to the supporting uprights to dispose theback rest in the desired elevation relative to the seat.

Another object of the invention is to provide a structure of this kindwherein it is practical to make the supporting uprights of metallictubing and wherein the back rest supporting arms are so attached to theuprights, by means partly inside and partly outside the same, that theback rest may be quickly adjusted as to height and positively locked inthe adjusted position.

The above mentioned objects of the invention, as well as others,together with the advantages thereof will more fully appear as thespecification proceeds.

In the drawing:

Fig. l is a perspective view of a back rest supporting structure forchairs, embodying the preferred form of the invention.

Fig. 2 is a detail vertical sectional view through parts of thestructure as taken on the line 2-2 and on a scale enlarged over that ofFig. 1.

Fig. 3 is a detail horizontal sectional view through a part of thestructure as taken on the line 3-3 of Fig. 2.

Fig. 4 is a view partly in elevation and partly in section of the upperends of the back rest supporting members and the associated connectingmember and illustrates more particularly the manner in which the ends ofsaid members are operatively connected together by corner fittingsdescribed in more detail later.

Fig. 5 is a horizontal detail sectional view as taken on the line 5-5 ofFig. 4

Fig. 6 is a perspective view of a sheet metal stamping which, when outtransversely, provides a pair of counterpart corner fittings by whichthe upper ends of the back rest supporting members and the associatedconnecting bridge are joined together.

Referring now in detail to that embodiment of the invention illustratedin the drawings, 10 indicates the seat of a chair which, for examle, maybe mounted on the upper end of a spindle 11, the lower end of which maybe mounted in a conventional manner in a supporting base, not shown.

12 indicates a back rest associated with the seat and which is mountedon the upper ends of a pair of laterally spaced uprights 13 disposed atthe back of the seat. These uprights are preferably made of squaremetallic tubing and in the upper end of those walls 14 of both uprights,which face each other, are longitudinal slots 15 that open through thetop edge of the associated wall. Engaged with the inner surfaces of theparts of each wall having a slot 15 therein is a slide 16 in the form ofa square piece of metal of a width approximating the inside widthbetween the walls. Fixed to each slide is a stud 17 which "ice extendsoutwardly through the slot in the associated wall 14, the free end ofeach stud being threaded. Journalled on each stud, outside theassociated upright, is a sleeve 18 having an inner end radial shoulder19 that engages the associated wall 14 at opposite sides of the slot 15ther in.

T e back rest 12 carries a pair of rearwardly extending relatively shortsupporting arms 20-20 spaced apart laterally a distance whichapproximates the distance between the walls 14 of the spaced uprights.The rear ends of said arms are journalled on the sleeves 18 and arespaced from the adjacent wall 14 by means of the shoulder 19 on eachsleeve. The sleeves each have an axial length, slightly more than thethickness of the associated arm 20 and on the threaded end of each studis located a combined washer and cap nut assembly 21. When the assemblyis drawn up tight it engages the end of the associated sleeve and whileit prevents displacement of the arm from the sleeve it does not bindagainst the arm:to prevent rocking movement on the sleeve. Also, whenthe washer and nut assembly is drawn up tight, it acts through the studto draw the slide into clamping engagement with the wall 14 of theassociated upright and this holds the stud in that position to which itwas adjusted longitudinally of the associated upright. At least one ofthe back rest supporting arms 20 is provided with an outwardly punchedshoulder 22, so disposed in the length of the arms as to be engageablewith the front of the associated upright to limit the downward rockingmovement of the back rest about the axis of the studs.

Loosening the washer and nut assemblies 21 releases the clamping actionfrom the studs 17 so that they may be adjusted into the desired positionlongitudinally of the associated slots 15. By tightening the assemblies,the clamping action is restored so as to hold the studs in the adjustedposition.

The top ends of the upright are connected together by a bridge member 23in connection with a pair of corner fittings 24-24, the bridge memberpreferably being made of square metallic tubing.

In making up the corner fittings, they are preferably made incounterpart pairs, each of which are thereafter separated into the twoindividual corner fittings. In so producing the corner pieces eachcounterpart pair is made of a die formed stamping 25 such as appears inperspective in Fig. 6, which is then cut transversely along the dottedline 25a to form two counterpart corner fittings 24. Each corner pieceincludes substantially triangular-1y shaped sides 26-26 with a roundedoutside wall 27, the side and outside walls having inwardly offsetextensions 28 connected thereto by a shoulder 29. These extensions aredisposed to have a telescopic fit within the upper end of an associatedupright 13 with the top edge of the upright abutting the shoulder 29.Screws 30 are passed through the front and rear walls of each upright,at their upper ends, and are threaded into flanged openings in oppositeportions of the extensions 28.

The bridge member 23 is also made of square tubing of such a crosssectional area as to fit within the open sides of each fitting, and saidends are so fitted and then welded therein before the extensions 28 aretelescoped into the open top ends of the uprights and secured thereto bythe screws 30 as heretofore mentioned. When the parts have been thusassembled the end portions of the bottom wall of the bridge member restsupon the top edges of the wall of the uprights having the slots 15therein and they thus close off the top ends of the slots in said wallsof the uprights. The bridge member 23 is so disposed as to act as a stopfor the upward rocking movement of the back rest.

The corner fittings provide a strong rigid connection between theassociated ends of the bridge member and uprights respectively andprovides a smooth corner surface therefor.

I claim as my invention:

1. In a back rest supporting structure for chairs, laterally spacedtubular uprights, each including a part at the upper end thereof havinga longitudinal slot said part having the slot therein comprising a wallwith a face portion which confronts the face portion of the otherupright, a slide engaged with the inner face of said part of eachupright, a stud carried by said slide and extending through theassociated slot, a sleeve on each stud and having a radial end shoulderengaged with the adjacent surface of the associated part of an upright,a back rest, supporting arms on said back rest, one journalled on eachsleeve and engaged with the shoulder thereof, said sleeve having anaxial length greater than the thickness of an arm, and a member threadedupon the end portion of each stud and engaged with the exposed end ofthe sleeve thereon, for holding the arm on said sleeve againstdisplacement and for clamping each slide and stud to the associated partof an upright.

2. In a back rest supporting structure for chairs, laterally spaceduprights each being tubular at the upper end and in which end is alongitudinal slot, a slide in the upper end of each upright, a studcarried by said slide and extending out through the associated slot, asleeve on each stud and having a radial end shoulder engaged with theouter surface of the upper end of the associated upright, a back rest,supporting arms on the back rest, one arm journalled on each sleeve andengaged with the shoulder thereof, said sleeve having an axial lengthgreater than the thickness of an arm, and a member threaded upon the endportion of each stud and engaged with the exposed end of the sleevethereon, for holding the arm on the sleeve against displacement andforhclamping each slide and stud to the associated uprig t.

3. In a back rest supporting structure for chairs, laterally spacedtubular uprights of rectangular cross section having a plurality ofwalls, the inner wall of each upright having a longitudinal slot in itsupper portion, a slide disposed in the upper portion of each upright andengaged with one surface of the inner wall thereof, a stud carried byeach slide and extending out through the associated slot, a sleeve oneach stud and having a radial end shoulder engaged with the outersurface of the wall of the associated upright, a back rest, supportingarms on said back rest, one journalled on each sleeve and engaged withthe shoulder thereof, said sleeves having axial lengths greater than thethickness of said arms, and a member threaded upon the end portion ofeach stud and engaged with the exposed end of the sleeve thereon, forholding the arm on said sleeve against displacement and for clampingeach slide and stud to the associated wall of an upright.

4. In a back rest supporting structure for chairs, laterally spaceduprights each including an upper end portion having a longitudinal slottherein that opens through a face of said portion that confronts a faceportion of the opposite upright, members each carried by a part of saidend portion of each upright and having engagement with opposed wallportions of said uprights to form a non-rotative sliding guidedengagement therewith, a stud carried by each member and extending outthrough the slot in said portion, a sleeve on each stud having a part ofone diameter and another part of a greater diameter engaged with saidadjacent face of an associated upright, a back rest, supporting arms onthe back rest, each journalled on the exposed end of a sleeve and havinga thickness less than the axial length thereof, and a means on each studoutwardly of but engaged with said sleeve for holding said arm againstdisplacement therefrom and for clamping each member and its stud to theassociated end portion of its upright.

5. In a back rest supporting structure for chairs, laterally spaceduprights and a member connecting upper end portions thereof, a back restarranged forwardly of said portions of said uprights, means providingrearwardly extending supporting arms on said back rest, means positionedsubstantially in the central vertical plane of said spaced uprights andproviding a pivotal connection for the rear ends of said arms, each withan associated upright for a rocking movement, said arms having partspunched laterally outward therefrom, each part for engaging a part ofthe associated upright to limit the rocking movement of the back restand said arms in one direction, rocking movement of said back rest andsaid arms in the other direction being limited by the engagement of theback rest with said connecting member.

References Cited in the file of this patent UNITED STATES PATENTS

